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Abstract
Quantification of PM2.5 (particulate matter <2.5 µm) bound heavy metals and their potential health risks were carried out around a cement manufacturing company in Ewekoro, Nigeria. The PM2.5 samples were collected using Environtech gravimetric sampler. A four-staged sequential extraction procedure was used to fractionate PM2.5 bound chromium (Cr), lead (Pb), aluminum (Al), copper (Cu), and silver (Ag), and further analyzed using inductively coupled plasma mass spectrometry. Chemical speciation results reveal bioavailable levels of Pb (4.05 µg/m3), Cr (10.75 µg/m3), Al (16.47 µg/m3), Cu (4.38E-01 µg/m3), and Ag (1.22E-02 µg/m3) in the airborne particulates. Pb and Cr levels exceeded the World Health Organization allowable limit of 0.5 and 2.5E-05 µg/m3, respectively. The labile phases showed strong indication of the presence of Cr and Cu metal. Excess cancer risks exposure for adults, outdoor workers and children were higher than the acceptable risk target level of 1E-06. Non-carcinogenic health risk estimated using hazard quotients (HQs) and hazard indices (HIs) showed ingestion route within the safe level of HI <1 implying no adverse effect while inhalation route exceeded the safe level for all receptors. Enforcement of pollution control by authorized agencies, and screening of greenbelts as sinks for air pollutants is strongly recommended.
Acknowledgments
The authors gratefully thank Prof. Zhang Suojiang, the Director of the Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China, for providing necessary laboratory support and Covenant University, Ota, Nigeria for providing a research base for this work. Also, we appreciate the anonymous reviewers for their constructive comments and suggestions.
Disclosure statement
No potential conflict of interest was reported by the authors.